class_docstr: Class that downloads a dataset and caches it locally.
  Assumes that the file can be downloaded (i.e. publicly available via a URI)
code: def _format_time_column(self, df):
      df[self._metadata.header_time] = pd.to_datetime(
          df[self._metadata.header_time],
          format=self._metadata.format_time,
          errors="raise",
      )
      return df
  
imports: import hashlib
  import os
  import tempfile
  import zipfile
  from abc import ABC, abstractmethod
  from dataclasses import dataclass
  from pathlib import Path
  from typing import Callable, List, Optional, Union
  import pandas
  import requests
  from darts import TimeSeries
  from darts.logging import get_logger
label_desc: Use image node_id 9 for calling the DatasetLoader obj's underlying member method code with example usage: obj._format_time_column(df) and returns: df